Product Details:
General Information:  This dynamic noise canceling mike type handset is the standard for many PRC-nnn series radios.  This handset was designed for use under combat conditions which includes explosions, heavy trucks or tanks driving nearby, etc.Handset H-250/U utilitizes a 1000 ohm earphone element, a 150 ohm dynamic noise canceling microphone, a push-to-talk switch and a six foot (extended) retractile cord terminating in a 5 pin audio connector (U-182/U). It is intended for use with military man-pack radio equipment such as the AN/PRC-70 and AN/PRC-77. Handset H-250/U can be uesd in place of Handset H-189/GR. NSN: 5965-00-043-3463.Ohmeter Readings:

• A (gnd) to B (ear) = 1,000 Ohms
• A (gnd) to C (PTT) = normally open, 6 Ohms PTT pressed
• A (gnd) to D (mike) = normally open, 150 Ohms PTT pressed
• A (gnd) to E (External) = always open Speaker